Pyrotechnic device



1964 E. H. WHEELWRIGHT ETAL 3,120,183

PYROTECHNIC DEVICE Filed Feb. 1, 1961 United States Patent 3,120,183 PYRiBTECHNlC DEVICE Edward Hartley Wheeiwright, Donald John Bonness, Ron. aid Henry MacDonald, and Garden Wilfred Curtis, Salisbury, England, assignors to Waeco Limited, Salisbury, England, a British company Filed Feb. l, 1961, Ser. No. 86,379 Claims priority, application Great Britain Mar. 21, 1960 9 (Zlainrs. (Cl. l02-32) This invention comprises improvements in or relating to pyrotechnic devices and is concerned more particularly with pyrotechnic devices such as smoke generating distress signals for marine purposes.

According to the present invention, a smoke generatling pyrotechnic device comprises a tubular body of a material having a low thermal conductivity but good resistance to heat, the smoke generating composition being contained in the body.

Heretofore, the body of a smoke generating pyrotechnic device has been made of metal so as to withstand the heat generated in use. It has now been found that a metal body reduces the performance of such pyrotechnic devices. For instance, if the smoke generating device is discharged in a cold atmosphere, or when floating in water as when the device is a marine distress signal, considerable condensation of the water vapour in the combustion products occurs by contact with the cold body so reducing the volume of issuing smoke and its brilliance, and further when the composition is initially ignited at the upper end of the body the condensation may be so great as to extinguish combustion before the smoke-generating composition is fully burned.

By employing, a heat resistant, low thermal conductivity' material for the body, such as resin bonded paper, the extent of water vapour condensation is greatly reduced so improving the performance of the pyrotechnic device by giving an increased volume of smoke, and also, when top ignition is employed, by reducing the risk that combustion is extinguished before the whole of the composition is burnt. This is of course of considerable importance when the pyrotechnic device is a marine distress signal. The use of materials such as resin-bonded paper also gives rise to advantages in manufacture and storage, since the material can readily be produced in seamless tube form of accurate dimensions, and is water proof and does not corrode or deteriorate.

In a preferred embodiment, the pyrotechnic device is a marine distress signal, the tubular body having fitted in it at one end a water-activated cell, a fuse connected to the cell to be ignited electrically when the cell is activated and an initiator for starting combustion of the smoke generating composition, and having at its other end a baffled outlet arrangement. The device also comprises a buoyancy float externally of the tubular body at a position spaced from the outlet end but nearer this end than the cell end.

According to a feature of this invention, the buoyancy float may be provided with cavities housing further Water-activated cells for energising light bulbs on the top of the float. Alternatively the lights may be energised by the cell employed for initiating combustion of the smoke generating composition.

3,i2fl,i8fi Patented Feb. 4,1954

One :form of marine distress signal incorporating the invention is illustrated in the accompanying drawing which is a longitudinal section through the signal.

The signal comprises a seamless tubular body ll} of resin-bonded paper for instance tube sold under the trade name Lantex, housing a carge ll of smoke generating composition. The charge may be in solid form, and may be of graduated density to control burning, or may be in pellet form the pellets being of graduated density if desired.

The charge may as shown, he in a further container Ila of metal or resin bonded paper, which is a sliding fit in the tubular body 10.

A perforated disc 12 is provided at each end of the charge 11 and a perforated tube 13 extends centrally through the charge from one end to the other. The tube 13 may be formed from expanded nylon having relatively large perforations.

At its lower end, the tube 10 has fitted in it three distance pieces or collars l4, l5, 16, there being a water seal 17 between each pair of collars, and a further seal 18 closes the lower end of the tube. The space 19 within collar 16 houses a water-activated cell which is inert until the device is thrown into the water, and the space 29 within collar 15 houses a fuse which is connected to the cell to be electrically ignited when the cell becomes active. The space 21 within collar 14 houses a combustion initiator for the main charge 11, the initiator being ignited by the tuse.

At its upper end, the body it) has fitted in it a series of collars 22 and discs 23 which are held in spaced relation by the collars. Each disc 23 has a hole 24- in it, the holes being diametrically opposite in adjacent discs. The holes in the lowermost discs may be closed by rupturable seals or polythene caps, the hole in the top disc 23 is closed by a rupturable seal or polythene cap or plug 25. The discs 23 form a baflled outlet for the smoke.

The device also comprises a buoyancy float 26 which may be formed of a foamed plastic, such as that marketed under the trade name Polyzote, which is highly shock resistant and is non-corroding, the float being secured to the body 10 between its ends but closer to the upper end than the lower end. The position of the float 25 is selected so that the device floats upright in water with its outlet end above the water surface.

The float 26 has one or more cavities formed in it to receive further water-activated cells 27 for energising light bulbs mounted on the top of the float. The bulbs are covered by transparent domes 23.

The device is compact and has a good performance since excessive condensation of water vapour does not occur even when the tubular body 10 is immersed in relatively cold water. The device is simple to manufacture and has improved storage properties as compared with metal cased signals. Also, the device can withstand long exposure to sea air and the shock of high falls into the sea at speed.

Also, in use, the lights on the float are unlikely to be shrouded by the issuing smoke since they are disposed Well below the smoke outlet.

In an alternative arrangement, the charge 11 is top ignited and in this case the initiator, at least is located between the upper end of the charge and the bafiled outlet. The fuse may also be at the top and connected to the cell by wires running the length of the device. The wires may be embedded in the tubular body We claim:

1. A marine distress signal comprising (a) a seamless tubular outer casing of resin bonded water-resistant heat-insulating material,

(12) a charge of a pyrotechnic smoke generating composition,

(c) an inner tubular casing housing said charge, the inner tubular casing being a sliding fit within said outer casing and having its ends spaced lengthwise from the ends of the outer casing,

(d) a series of spaced discs within one end of said outer casing beyond the inner casing, said discs hav ing apertures therein and forming a baffled smoke outlet at said one end of the outer casing,

(e) ignition means for the charge, said ignition means including (6 a Water-activatable electric cell accommodated in the outer casing at its other end beyond the adjacent end of the inner casing,

(e an electrically-ignitable fuse connected to said cell, and

(2 a combustion initiator connected to be ignited by the fuse and to ignite the charge,

(1) a perforated tube extending through the charge from one end thereof to the other end,

(g) a float of buoyant material secured externaliy of the outer casing to minimize shrouding by issuing smoke between its ends but closer to said one end of the outer casing,

(71) at least one light bulb mounted on said float, and

(i) an electric cell accommodated within said float and connected to energize the light bulb.

2. A marine distress signal comprising (a) a seamless tubular outer casing of resin bonded water-resistant heat-insulating material,

(b) a charge of a pyrotechnic smoke generating composition,

(c) an inner tubular casing housing said charge, the inner tubular casing being a sliding fit Within said outer casing and having its ends spaced lengthwise from the ends of the outer casing,

(d) a series of spaced discs within one end of said outer casing beyond the inner casing, said discs having apertures therein and forming a baflied smoke outlet at said one end of the outer casing,

(e) ignition means for the charge, said ignition means including (e a water-activatable electric cell accommodated in the outer casing at its other end beyond the adjacent end of the inner casing,

(e an electrically-ignitable fuse connected to said cell, and

(e a combustion initiator connected to be ignited by the fuse and to ignite the charge,

(f) a perforated tube extending through the charge from one end thereof to the other end, and

(g) a float of buoyant material secured externally of the outer casing between its ends but closer to said one end of the outer casing to minimize shrouding by issuing smoke,

(h) and water-activatable illuminating means mounted on said float.

3. A marine distress signal comprising (a) a seamless tubular outer casing of resin bonded water-resistant heat-insulating material,

(b) a charge of a pyrotechnic smoke generating composition,

(c) an inner tubular casing housing said charge, the inner tubular casing being a sliding fit within said outer casing and having its ends spaced lengthwise from the ends of the outer casing,

( a series of spacer discs Within one end of said outer casing beyond the inner casing, said discs having apertures therein and forming a baffled smoke outlet at said one end of the outer casing,

(e) ignition means for the charge, said ignition means including (e a water-activatable electric cell,

(e an electrically-ignitable fuse connected to said cell, and

(6 a combustion initiator connected to be ignited by the fuse and igniting the charge,

(e said cell, said fuse and said initiator being housed in the outer casing at the other end thereof in separate spaces sealed from one another,

(f) a perforated tube extending through the charge from one end thereof to the other end, and

g) a float of buoyant material secured externally of the outer casing between its ends but closer to said one end of the outer casing to minimize shrouding by issuing smoke, and

(/1) electric illuminating means mounted on said float including means to provide for a circuit through the illuminating means through contact with water.

4. A marine distress signal comprising (a) a seamless tubular outer casing of resin bonded water-resistant heat-insulating material,

(b) a charge of a pyrotechnic smoke generating composition,

(c) an inner tubular casing housing said charge, the inner tubular casing being a sliding fit within said outer casing and having its ends spaced lengthwise from the ends of the outer casing,

(d) means defining a bafiled outlet within one end of said outer casing beyond the adjacent end of said inner casing,

(e) ignition means for the charge, said ignition means including (0 a water-activatable electric cell accommodated in the outer casing at its other end beyond the adjacent end of the inner casing,

(6 an electrically-ignitable fuse connected to said cell, and

(e a combustion initiator connected to be ignited by the fuse and to ignite the charge,

(1) a perforated tube extending through the charge from one end thereof to the other end, and

(g) a float of buoyant material secured externally of the outer casing between its ends but closer to said one end of the outer casing to minimize shrouding by issuing smoke, and

(/1) electric illuminating means mounted on said float including means to provide for a circuit through the illuminating means through contact with water.

5. A smoke generating device according to claim 4, the initiator being located between the charge and the bafiied outlet.

6. A smoke generating device according to claim 5 wherein the fuse is also located between the charge and the baffled outlet and is connected to the cell by wires running the length of the device.

7. A smoke generating device according to claim 6, wherein the wires are embedded in the tubular body.

8. A smoke generating device according to claim 4, the buoyancy float having cavities therein, water-activated electric cells in said cavities, and light bulbs mounted on the top of the float and connected for energization to said cells.

9. A marine distress signal comprising (a) a seamless tubular outer casing of resin bonded water-resistant heat-insulating material,

(b) a charge of a pyrotechnic smoke generating composition,

(c) an inner tubular casing housing said charge, the inner tubular casing being a sliding fit within said outer casing and having its ends spaced lengthwise from the ends of the outer casing,

(d) means defining a baflled outlet within one end of said outer casing beyond the adjacent end of said inner casing,

(e) ignition means for the charge, said ignition means including (2 a water-activatable electric cell accommodated in the outer casing at its other end beyond the adjacent end of the inner casing,

(e an electrically-ignitable fuse connected to said cell, and

(e a combustion intiator connected to be ignited by the fuse and to ignite the charge,

(f) a perforated tube extending through the charge from one end thereof to the other end,

(g) a float of buoyant material secured externally of the outer casing between its ends but closer to said one end of the outer casing,

(h) at least one light bulb mounted on said float and (i) an electric cell accommodated within said float and connected to energize the light bulb.

References Cited in the file of this patent UNITED STATES PATENTS 2,423,859 Van Karner July 15, 1947 2,859,695 Rolle Nov. 11, 1958 2,923,930 Del Mar Feb. 2, 1960 2,978,716 Jackson Apr. 11, 1961 

1. A MARINE DISTRESS SIGNAL COMPRISING (A) A SEAMLESS TUBULAR OUTER CASING OF RESIN BONDED WATER-RESISTANT HEAT-INSULATING MATERIAL, (B) A CHARGE OF A PYROTECHNIC SMOKE GENERATING COMPOSITION. (C) AN INNER TUBULAR CASING HOUSING SAID CHARGE, THE INNER TUBULAR CASING BEING A SLIDING FIT WITHIN SAID OUTER CASING AND HAVING ITS ENDS SPACED LENGTHWISE FROM THE ENDS OF THE OUTER CASING, (D) A SERIES OF SPACED DISCS WITHIN ONE END OF SAID OUTER CASING BEYOND THE INNER CASING, SAID DISCS HAVING APERATURES THEREIN AND FORMING A BAFFLED SMOKE OUTLET AT SAID ONE END OF THE OUTER CASING, (E) IGNITION MEANS FOR THE CHARGE, SAID IGNITION MEANS INCLUDING 